1. Field of the Invention
This invention relates to an annular radial flow gas turbine engine and a disc type airborne vehicle employing same in conjunction with thrust and aerodynamic surface control means enabling the vehicle to take off and land vertically, to hover and to engage in both low speed and high speed aerodynamic flight.
2. Description of the Prior Art
The broad concept of an aircraft powered by a radial flow gas turbine engine is old, such as disclosed in Smith U.S. Pat. No. 2,850,250. In the engine disclosed by Smith, an internal set of stator blades is required for the compressor and turbine sections which adds weight to and unduly complicates the engine. Air input to the first stage of the compressor is restricted due to a plurality of conduits or openings of somewhat smaller diameter than the opening to the compressor. This feature together with the counter-rotational rotor blades creates a noncontinuous flow of air to the compressor input. Also, the Smith engine employs a plurality of so-called "can type combustion chambers" of relatively limited volumetric capacity per given weight and which of themselves simply house the combusting products, i.e. contribute no turbulence or mixing effect to the fuel air mixture or combusting products. It is also a disadvantage of the engine and aircraft arrangement disclosed by Smith that the products of combustion emitting from the annular array of combustion chambers are simply ducted in essentially only one direction from the craft.
Heinze U.S. Pat. No. 1,868,143 discloses a turbine engine utilizing a premixture of fuel and air for communication to a compressor comprising counter-rotational blades. This premixture is drawn into the compressor through an input chamber of relatively small diameter by a hollow rotating shaft having a plurality of holes at one end. As in the Smith patent, this feature creates a noncontinuous flow of premixed fuel and air to the compressor input. Heinze also teaches the use of a rectangular shape combustion chamber with a capacity of at least three times that of an input chamber in communication therewith prior to compression. This configuration has inherent safety and operational disadvantages in that Heinze discloses the compression of a potentially explosive fuel air mixture while providing a combustion chamber of a geometric shape insufficient to sustain combustion.
Frost et al Canadian Pat. Nos. 683,142 and 787,245 present essentially identical disclosures of disc type aircraft with essentially identical radial flow gas turbine engine propulsion systems. In the Frost et al propulsion systems the engines also require compressor and exhaust stator blading and also employ stationary can type combustion chambers with the same disadvantages as discussed above with respect to Smith. A further and significant disadvantage of the Frost et al engine is its use of a single rotating compressor and turbine element interfacing with corresponding stator elements in contrast to use of counter-rotating elements in the manner characteristic of the present invention. A single rotating compressor and turbine element result in excessive torque and the direction of the rotor rotation and also causes large gyroscopic precessional forces presenting serious design and operational complication in the practical use of this type of engine. Further, although Frost et al discloses the use of air bearings to support radial and axial loads, the Frost et al engine provides no conventional mechanical bearings for support of the rotor portions of the engine during engine start-up and shut-down and during other engine operating conditions when air bearings alone do not entirely satisfy required engine tolerances.
Mulgrave et al U.S. Pat. No. 2,997,254 discloses the use of lift means annularly disposed beneath a vehicle. Forward propulsion of the vehicle is provided by a plurality of panels sequentially disposed about the upper surface of the vehicle. Although Mulgrave teaches the use of the propulsion in the forward direction by ducting a portion of the exhaust gases, such propulsion is not accomplished by a continuous annular ducting means generally disposed peripherally around the underside of the vehicle.
Freeland U.S. Pat. No. 3,045,951 shows a propulsion ducting system which appears to be continuous but is on the horizontal side of a vehicle and is not disposed peripherally beneath the vehicle.
McDevitt U.S. Pat. No. 3,568,955 although showing annular propulsion means disposed beneath a vehicle, does not teach the use of a continuous annulus of forward propulsion. In McDevitt, forward propulsion is provided by four dampers located at opposite ends of the vehicle.
Finally, viturally all aircraft gas turbine engines in present use are of the axial flow type providing only point thrust axially of a jet nozzle and aircraft using this type of engine must be designed accordingly. While axial flow gas turbine engines have been used for propulsion purposes in a few prototype vertical take-off and landing vehicles, the design limitations dictated by the inherent point thrust of the axial flow type engine necessitates extensive exhaust ducting and control features with the result that these vehicles have met with only modest overall success.